Integrated surgical microscope and wavefront sensor

ABSTRACT

A wavefront sensor is integrated with a surgical microscope for allowing a doctor to make repeated wavefront measurements of a patient&#39;s eye while the patient remains on an operating table in the surgical position. The device includes a wavefront sensor optically aligned with a surgical microscope such that their fields of view at least partially overlap. The inclusion of lightweight, compact diffractive optical components in the wavefront sensor allows the integrated device to be supported on a balancing mechanism above a patient&#39;s head during a surgical procedure. As a result, the need to reposition the device and/or the patient between measuring optical properties of the eye and performing surgical procedures on the eye is eliminated. Many surgical procedures may be improved or enhanced using the integrated device, including but not limited to cataract surgery, Conductive Keratoplasty, Lasik surgery, and corneal corrective surgery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/021,594, entitled “INTEGRATED SURGICAL MICROSCOPE AND WAVEFRONTSENSOR,” and filed Feb. 4, 2011, which is a continuation of U.S. patentapplication Ser. No. 11/110,653, entitled “INTEGRATED SURGICALMICROSCOPE AND WAVEFRONT SENSOR,” and filed Apr. 20, 2005, which claimsthe benefit of U.S. Provisional Application No. 60/563,727, filed Apr.20, 2004, each of which is incorporated by reference in their entiretyas if fully set forth herein.

BACKGROUND

Refractive surgery and other corrective procedures are commonlyperformed on the human eye. During a refractive surgical procedure, therefractive quality of the eye is altered. The goal of refractive surgerytypically is to correct a defective refractive condition of the eye,while not diminishing the overall refractive quality of the eye. In somecases, the goal is to actually improve the overall refractive quality ofthe eye.

Refractive measurements are typically taken with phoroptors,pachymeters, corneal topographers, autorefractors, keratometers, and/orwavefront sensors. Of these devices, wavefront sensors generally providethe greatest detail about the refractive condition of, and additionalinformation relating to, the eye. Wavefront sensors are generallystandalone devices that operate in relatively large areas dedicated tothe use of the wavefront sensors. With most existing wavefront sensors,the patient's eye is measured while the patient is in a sittingposition.

Many methods of performing refractive eye surgery requirepre-operatively measuring the refractive quality of a patient's eyeusing a wavefront sensor or other measuring device. This refractivequality information is used to plan a detailed refractive surgicalprocedure. The patient is then typically moved from the wavefront sensorlocation to a surgical location, where the patient lies supine in the“surgical position.” During the refractive surgical procedure, thesurgeon may view the patient's eye through a surgical microscope orother viewing device, which typically is suspended above the patient'shead via a balancing mechanism or other similar device. Once therefractive surgical procedure is completed, the patient is typicallymoved back to the wavefront sensor location, and the eye is measured todetermine the outcome of the surgery.

Although measuring the refractive quality of the eye after therefractive surgery has been performed provides a quantification of theoutcome of the surgery, it does not allow modifications to the surgeryto be performed while the patient remains in the surgical position. Ifthe outcome is not ideal, the patient may be relocated to the surgicalarea for a re-treatment, but in many cases a re-treatment may not be aseffective as if the procedure had been performed to produce an idealresult the first time before the patient was moved from the surgicalposition. Additionally, moving a patient out of the sterile surgicalfield for diagnostic purposes, and then back into the surgical field,can be problematic.

If the refractive quality of the eye could be measured repeatedly as thesurgery is progressing, without moving the patient, the surgeon wouldhave the opportunity to judge whether the procedure was producingdesired results at the expected rate, and would be able to makeadjustments or course corrections to the procedure midstream to improvethe likelihood of achieving the desired outcome. Unfortunately, existingwavefront sensors and other measuring devices are generally relativelylarge and heavy, making them impracticable or impossible to suspendabove a patient's head during surgery. As a result, a patient must bephysically moved between wavefront measurement procedures and surgicalcorrection procedures that are typically performed under a surgicalmicroscope.

While attempts have been made to integrate a microscope into acomprehensive treatment and measurement device, such devices aretypically very large, heavy, and cumbersome, such that they cannot bepractically suspended above a patient lying in the surgical position.These devices also typically include shared lenses and other opticalcomponents. The sharing of optical components in this manner generallyobscures the overall quality of the measurements that are produced,since each device component typically has its own set of opticalrequirements that cannot each be optimally satisfied using shared lensesand so forth. Thus, a need exists for an improved device for measuringand evaluating refractive and other optical properties andcharacteristics of an eye.

SUMMARY OF THE INVENTION

A wavefront sensor is integrated with a surgical microscope for allowinga doctor to make repeated measurements of a patient's eye while thepatient remains in a surgical position. The device includes a wavefrontsensor optically aligned with a surgical microscope such that theirfields of view at least partially overlap. The optional inclusion oflightweight, compact diffractive optical components in the wavefrontsensor allows the integrated device to be supported on a balancingmechanism above a patient's head during a surgical procedure. As aresult, the need to reposition the device and/or the patient betweenmeasuring optical properties of the eye and performing surgicalprocedures on the eye is eliminated.

Other features and advantages of the invention, including methods ofusing the device described above, will appear hereinafter. The featuresof the invention described above can be used separately or together, orin various combinations of one or more of them. The invention resides aswell in sub-combinations of the features described.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein the same reference number indicates the sameelement throughout the several views:

FIG. 1 is a side view of an integrated wavefront sensor and surgicalmicroscope positioned above a patient's head.

FIG. 2 is a top view of the internal components of a wavefront sensor(with the cover removed) according to one embodiment.

FIG. 3 is a perspective view of an aberrated wave traveling through agrating, as well as wave images produced at the first and second Talbotplanes of the grating.

FIG. 4 is a side-view schematic diagram illustrating the operation of anintegrated wavefront sensor and surgical microscope according to oneembodiment.

FIG. 5 is a front-view schematic diagram of the operation of theintegrated wavefront sensor and surgical microscope illustrated in FIG.4.

DETAILED DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described. Thefollowing description provides specific details for a thoroughunderstanding and enabling description of these embodiments. One skilledin the art will understand, however, that the invention may be practicedwithout many of these details. Additionally, some well-known structuresor functions may not be shown or described in detail so as to avoidunnecessarily obscuring the relevant description of the variousembodiments.

The terminology used in the description presented below is intended tobe interpreted in its broadest reasonable manner, even though it isbeing used in conjunction with a detailed description of certainspecific embodiments of the invention. Certain terms may even beemphasized below; however, any terminology intended to be interpreted inany restricted manner will be overtly and specifically defined as suchin this detailed description section.

Referring to FIG. 1, a surgical device 10 includes a surgical microscope12, or other suitable viewing device, attached to a wavefront sensor 14,or other measuring device. The surgical microscope 12 includes aneyepiece 16, or other viewing mechanism, which includes one or moreoptical channels each having one or more optical lenses therein. Theeyepiece 16 is preferably binocular, or stereo, in that it includes twooptical channels for allowing a doctor to view an eye 18 of a patient 20using both of the doctor's eyes (as is best seen in FIG. 5). While amonocular eyepiece may alternatively be used, a binocular eyepiece isgenerally preferred because it provides a higher quality, more completeview to the doctor.

The surgical microscope 12 preferably further includes a light source 22for providing visible light into the optical pathway of the eyepiece 16,a focusing knob 24 for adjusting the focus of the microscope 12, and anobjective lens 26, or other suitable lens, for focusing light beams. Inone embodiment, the objective lens 26 is threaded onto the microscope 12via internal threads on the lens 26 that match external threads on abody 25 of the microscope 12.

The wavefront sensor 14 may be attached to the microscope 12 in anysuitable manner, and is preferably removably attached to the microscope12. For example, the objective lens 26 may be removed from themicroscope 12, and the wavefront sensor 14, which preferably includes anattachment portion with interior threads that match the exterior threadsof the microscope body 25, may be screwed onto the external threads ofthe microscope 12. The objective lens 26 may then be screwed back ontothe external threads beneath the attachment portion of the wavefrontsensor 14. One or more fasteners 28 may optionally be included tofurther (or alternatively) secure the wavefront sensor 14 to themicroscope 12. The wavefront sensor 14 may alternatively be attached tothe microscope via screws, bolts, pins, clamps, adhesive, or any othersuitable fasteners or attachment means.

Referring to FIG. 2, the interior of one embodiment of a wavefrontsensor 14 is illustrated. The wavefront sensor 14 includes a lasersource 40, or other light source, for creating a beam of light,preferably infrared light. During operation, the beam of infrared lightis preferably directed by a mirror 42 toward a beam splitter 44 or othersuitable device. An aperture-sharing element, such as a combiner mirror46 (shown in dashed lines in FIG. 1), a beam-splitter, or other similardevice, reflects the beam of infrared light down into the eye 18 of thepatient 20. The combiner mirror 46 preferably reflects infrared lightwhile transmitting visible light so that a doctor can see the patient'seye 18 while looking through the combiner mirror 46. The combiner mirror46 may alternatively be configured to reflect a portion of the visiblelight spectrum, and/or to transmit a portion of the infrared lightspectrum, as described below.

After the infrared light beam enters the eye 18, it is reflected, as awavefront, from the retina of the eye 18 toward the combiner mirror 46.The combiner mirror 46 redirects the light beam through the beamsplitter 44 toward a first lens 48. The first lens 48 relays theinfrared light beam off of mirrors 50 and 52 toward a second lens 54,which directs the light beam onto a diffractive optical component, suchas a first reticle or grating 56. The mirrors 42, 50, 52 are optionallyincluded in the wavefront sensor 14 for re-directing the light beam tomaintain it within a compact area, which facilitates the minimization ofthe overall size and length of the wavefront sensor 14. A greater orlesser number of mirrors may be included in the wavefront sensor 14.

The light beam is diffracted by the first grating 56, as described indetail below, and preferably travels through another diffractive opticalcomponent, such as a second grating 58, which further diffracts thelight beam and creates a final image of the wavefront reflected from theeye 18. A camera 60, and/or another light detector or sensor, such as aCCD camera or other suitable device, then captures, records, and/ordetects the final image of the eye 18 and converts it into acomputer-readable format. A computer may then measure and analyze thedata to quantify characteristics of the wavefront, and thus, therefractive properties of the eye being examined.

The wavefront sensor 14 may of course include a greater or lesser numberof components to meet the requirements of a given system. For example, agreater or lesser number of diffractive gratings or optical lenses maybe included in the wavefront sensor 14. Moreover, additional opticalcomponents, such as a camera lens, may optionally be included betweenthe second refractive grating 58 and the camera 60. Thus, the specificconfiguration of the wavefront sensor 14 illustrated in FIG. 2 is onlyone example a suitable wavefront sensor configuration.

Because the wavefront sensor 14 requires relatively few components, anduses relatively small, lightweight diffractive optical elements in itswavefront analysis section, the wavefront sensor 14 may be very compactand lightweight, and can produce higher resolution and more accuratealignment registration than a wavefront sensor using larger conventionalrefractive optics, such as a typical Hartmann-Shack wavefront sensor, asdescribed below. The wavefront sensor 14 preferably has a length Y thatis less than 10 inches, more preferably less than nine inches, morepreferably approximately 8.5 inches, and a width X that is preferablyless than 5 inches, more preferably approximately 4.5 inches. Thewavefront sensor 14 preferably weighs less, than five pounds, morepreferably less than 3 pounds or less than 2 pounds. The wavefrontsensor 14 may of course be any other suitable size and/or weight.

Due to its relatively low weight and small size, the wavefront sensor 14may be directly or indirectly attached to the surgical microscope 12 toform an integrated surgical device 10. In this sense, the term“integrated” generally refers to the wavefront sensor 14 and thesurgical microscope 12 being incorporated into a unit. The integratedsurgical device 10 may be attached to a balancing mechanism, hangingmechanism, or other suitable device or stand for suspending theintegrated device 10 over a patient's head during surgery. The balancingmechanism or other supporting device may be spring-loaded,counter-balanced, or otherwise balanced for supporting the integrateddevice 10. Balancing mechanisms of this nature are commonly used tosupport and suspend surgical microscopes.

To secure the integrated surgical device 10 to a balancing mechanism, anattachment portion 30 of the surgical microscope 12 (or of the wavefrontsensor 14) may be attached to the balancing mechanism via screws, pins,bolts, or other suitable fasteners, or the integrated device 10 may beattached to the balancing mechanism in any other suitable manner. In oneembodiment, the wavefront sensor 14 may be added to an existing surgicalmicroscope 12 that is already supported on a balancing mechanism. Thefield of view and the focal length of the microscope 12 and/or thewavefront sensor 14 may then be adjusted, if necessary, to opticallyalign the devices relative to one another, as further described below.

Generally speaking, refractive optical components are used to redirect alight beam as it passes through a material having a higher density thanair, such as a glass refractive lens. Diffractive optical components,conversely, are used to bend a light beam as it encounters the sharpedges of an element, such as the gratings 56, 58, and only portions ofthe light beam occurring near the edges of the grating or other objectare redirected. Diffractive optical components, such as gratings, aretypically significantly smaller and weigh less than refractive opticalcomponents, such as refractive lenses.

The one or more diffractive gratings used in the wavefront sensor 14 maybe made of any suitable material. A preferred diffractive grating ismade from a clear material, such as glass, and has equally spacedperpendicular lines etched or otherwise present on its surface. Thegrating may include, for example, a repeating sequence of solid lineseach having a width of approximately 12.5 microns, with each pair oflines separated by approximately 12.5 microns of clear glass (the linesand glass spaces on the grating may of course have any other suitabledimensions). The same sequence is repeated with lines runningperpendicularly to the first set of lines, such that a pattern similarto that of a standard grid (i.e., a network of uniformly spacedhorizontal and perpendicular lines) is formed.

As illustrated in FIG. 3, when a wavefront of light reflected from aneye encounters a grating (referred to as the “Periodic Object” in FIG.3) diffractive effects begin to occur. Some of the light hits the solidportions of the lines on the grating and is prevented from passingthrough the grating. Some of the light passes cleanly through the clearspaces in the grating and is not affected by the grating lines. Theremaining light, however, encounters the edges of the solid lines as itpasses through the grating. This light is disturbed by the lines and isdeflected away from the central core of the light that passes cleanlythrough the clear spaces in the grating.

This redirected light encounters light that has been redirected by oneor more adjacent grating lines. When portions of light directed fromequally spaced lines meet one another, a phenomenon known as the “TalbotEffect” occurs, and a series of dark and light zones form in a spacewithin a predictable distance downstream from the grating, at locationsreferred to as Talbot planes. This phenomenon is described in detail inU.S. patent application Ser. No. 10/885,504, filed Jul. 6, 2004, as wellas in “Fourier Transform Method For Automatic Processing of MoireDeflectograms,” Quiroga et al., Opt. Eng. 38(6) pp. 974-982 (June 1999),and in “Refractive Power Mapping of Progressive Power Lenses UsingTalbot Interferometry and Digital Image Processing,” Nakano et al., Opt.Laser Technology. 22(3), pp. 195-198 (1990), all of which areincorporated herein by reference.

If the wavefront of light that passed through the grating is a flat,plane wave, the dark and light zones form a perfect replica of thegrating, i.e., a virtual image of the grating. If, however, thewavefront is aberrated or includes any deviations from a flat, planewave, the shape and size of the virtual image of the grating isdistorted, as shown in FIG. 3. By observing the distortions in the shapeand size of the virtual image created by the grating, thecharacteristics of the wavefront can be determined. The virtual imagemay be observed by a camera or other light detector, and the images maybe measured, typically by a computer, to accurately quantify thecharacteristics of the wavefront, and hence, the refractive propertiesof the eye being examined.

In one embodiment, two or more gratings are aligned in series in thewavefront sensor. By causing the virtual image to pass through the linepatterns in one or more additional gratings, the virtual image of thegrating is modified to show less resolution, which can compensate for acamera having insufficient resolution. Additionally, by adding one ormore gratings, and rotating the downstream gratings with respect to oneanother, the changes in the virtual image of the initial grating arevisually converted into rotational movement, rather than just shrinkageor expansion, and the characteristics of the wavefront may be determinedwithout change in size of the virtual image.

The virtual image created by the gratings contains, simultaneously, twosets of information. The first set of information is the virtual imageof the grating from which the refractive properties of the eye arecharacterized, as described above. The second set of information is analmost complete image of the pupil of the eye, which is comprised of thelight that passed untouched through the clear spaces of the grating, aswell as light that reflected from the surface of the pupil, the sclera,the limbus, and/or other features of the eye if additional illuminationis directed to illuminate these features. This image essentially appearsto be that of an eye being observed with a grid (i.e., a network ofuniformly spaced horizontal and perpendicular lines) between the eye andthe observer.

Referring to FIGS. 4 and 5, a schematic representation of a process formeasuring characteristics of an eye is shown. A surgeon (or otherdoctor) 105 looks through a surgical microscope 112 at the eye 125 of apatient. The surgical microscope 112 preferably includes binocular, orstereo, optics such that it includes two optical viewing channels 116,118 (as shown in FIG. 5). A monocular microscope may alternatively beused, however. Visible light reflecting from the patient's eye 125travels along a light pathway 150, passes through a combiner mirror 120or similar device, and into the microscope 112, so that the surgeon mayview the patient's eye 125 along visual pathways 122, 124.

A wavefront sensor 114 generates an infrared light beam and projects itoutwardly along a pathway 145 toward the combiner mirror 120. While thecombiner mirror 120 is shown located outside of the wavefront sensor 114in the schematic representation of FIGS. 4 and 5, it is understood thatthe combiner mirror 120 may be located inside the wavefront sensor 114,as is shown in FIGS. 1 and 2, or in any other suitable location wherethe optical pathways of the surgical microscope 112 and the wavefrontsensor 114 meet.

The combiner mirror 120 is preferably transparent to visible light butreflective to infrared light so that it reflects the infrared light beamtoward the patient's eye 125. The wavefront sensor 114 and themicroscope 112 preferably share a common aperture through the combinermirror 120. Alternatively, a beam splitter that transmits and reflectsboth a portion of the visible light and a portion of the infrared lightmay be used in place of the combiner mirror 120. Using such a beamsplitter would allow the wavefront sensor 114 to operate at a wavelengthother than that of the infrared light, such as at a wavelength in thevisible spectrum.

In another embodiment, the combiner mirror 120 may be configured toreflect a portion of the visible light spectrum, allowing the wavefrontsensor 114 to operate in a wavelength range within the visible spectrum,yet prevent that particular wavelength from entering the Microscope 112.In yet another alternative embodiment, the combiner mirror 120 may be anarrow pass/reflect combiner, which reflects only a defined wavelengthof light having a lower and upper range, thereby allowing the wavefrontsensor 114 to operate within the visible light spectrum. The definedvisible light spectrum would then be selectively blocked from returningto the microscope 112, while all light above or below the lower andupper ranges would be freely transmitted.

The combiner mirror 120 reflects the light beam along pathway 150 towardthe patient's eye 125. The infrared light enters the patient's eye 125and is reflected as a wavefront back along light pathway 150 toward thecombiner mirror 120, which reflects the wavefront along light pathway145 into the wavefront sensor 114. The wavefront sensor 114 thenmeasures the wavefront using the process described above, or using asimilar process. The wavefront sensor 114 may have the sameconfiguration and components as the wavefront sensor 14 illustrated inFIG. 2, or it may have an alternative configuration and may includealternative components.

The wavefront sensor 114 and the microscope 112 are each preferablyfocused at a point occurring at plane 135, such that a field of view 155of the wavefront sensor 114 at least partially overlaps a field of 160of the microscope 112. During measuring, viewing, and/or performingsurgery, the patient's eye 125 is preferably located within theoverlapping portion of the fields of view 155, 160. In a preferredembodiment, the wavefront sensor 114 and the microscope 112 are focusedat substantially the same point, such that the center of each field ofview 155, 160 is located at approximately the same point, in the sameplane 135, preferably at or near the center of the patient's eye 125.

As a result, the surgeon 105 may look through the microscope 112directly into the visual axis of the patient's eye 125 while thewavefront sensor 114 takes measurements of the eye 125. Furthermore,because the fields of view 155, 160 overlap at the patient's eye 125,the patient does not have to change the gaze angle of the patient's eye125 at any time during the viewing and measurement processes. This canbe very advantageous, especially when the surgical procedure beingperformed prevents the patient from seeing clearly, or at all, such thatit is nearly impossible for the patient to accurately adjust the gazeangle of the patient's eye 125 according to a surgeon's instructions.

The integrated wavefront sensor and surgical microscope described hereinprovides several advantages. First, it allows a surgeon or other doctorto directly view a patient's eye while the wavefront sensor performsmeasurements of the refractive characteristics or other opticalproperties of the patient's eye. As a result, a surgeon can view theresults of a given step of a surgical procedure without having to movethe patient, the patient's eye, or the device. Indeed, the gaze angle ofthe patient's eye does not need to change at all during the viewing andmeasuring steps, and the surgeon's view may be directly aligned with, asopposed to offset from, the visual axis of the patient's eye.

Additionally, due to the relatively small number of components used inthe wavefront sensor, and the relatively small size and low weight ofthose components, particularly of the one or more lightweightdiffractive gratings or other diffractive optical components, theintegrated device may be very compact. Accordingly, the lightweightintegrated device can be suspended on a balancing device, or othersupporting mechanism, above the head of a patient lying in the supinesurgical position, while the surgeon views the patient's eye through thesurgical microscope of the integrated device.

To maintain its compact size and design flexibility, the integratedsurgical device 10 is preferably not integrated with or otherwiseattached to a refractive laser device or other refractive surgical tool.Thus, the integrated surgical device 10 is preferably used primarily forviewing and measuring purposes, while one or more surgical tools used toperform corrective eye procedures are physically separate from theintegrated device. Lightweight or otherwise compact surgical tools,however, may optionally be incorporated into the surgical device 10. Thewavefront sensor 14 and the surgical microscope 12 also preferably donot share an optical pathway to the patient's eye 18 with any othersurgical devices.

Because the wavefront sensor and the surgical microscope are preferably(although, not necessarily) separate components that are removablyattached to one another, they may each include their own opticalcomponents, including any lenses. Thus, the wavefront sensor and thesurgical microscope do not need to share a lens, thus providing severaladvantages and general design flexibility over integrated surgicalsystems that require one or more lenses to be shared between two or moreoptical components.

Some surgical systems, for example, use a common optical lens to focuslight beams from both a wavefront sensor and a refractive laser device.By sharing a lens in this manner, the flexibility to select or designthe lens for only a single specific function is lost, as is the abilityto design the best possible lens for the overall system application. Byusing a common lens, compromises must be made to meet the requirementsof each component that shares the lens.

Antireflective coatings, for example, are commonly applied to lenses sothat they can function optimally within a certain wavelength. If thelaser being used is of a different wavelength than the wavefront sensorillumination beam, however, a common antireflective coating cannot beselected that will work optimally for each of the wavelengths. The sameholds true for the wavelength of the wavefront sensor illumination beamin comparison to that of the visible light used to provide visibilitythrough a microscope. Because the surgical device 10 described hereindoes not require that a lens be shared between the wavefront sensor andthe surgical microscope, different antireflective coatings may beapplied to the lenses of each of these components, thus allowing foroptimal coatings to be selected for each component.

Another disadvantage of sharing a common lens between two or moreoptical components is the inability to select an optimal focal length,or power, of the lens for each component involved. In many cases, a longfocal length lens is desirable in a wavefront sensor to providesufficient working space for a doctor between the wavefront sensor andthe patient. With many refractive lasers, conversely, a shorter focallength lens is desirable to more tightly focus the laser energy into ashorter plane. A system that shares a common lens for these componentsmust compromise or settle on a common focal length, which will not beoptimal for one or both of the components.

Additionally, if a wavefront illumination beam is projected through alens that is also used as an imaging lens for a microscope, a highlikelihood of “flashback glint” arises. Even when an optimalantireflective coating is applied to a lens (which likely cannot beachieved for a lens shared by multiple components, as described above),a certain amount of light will reflect from the lens surface as thelight enters the lens. This light reflects back into the wavefrontsensor, and is seen as a tiny bright flash of light, or “glint” Thisglint can obliterate the wavefront information of one or more portionsof the eye. Thus, an advantageous feature of the surgical device 10 isthat it does not require a lens to be shared by the wavefront sensor 14and the surgical microscope 12.

Other advantages result from the detachable nature of the integratedwavefront sensor and surgical microscope, as compared to existingdevices that are permanently integrated. For example, the option ofadding the compact wavefront sensor 14 to an existing surgicalmicroscope 12, or of moving the wavefront sensor 14 from one surgicalmicroscope 12 to another, or of removing the wavefront sensor 14 fromthe surgical microscope for another reason, such as to individuallyrepair one of the devices, provides a great deal of flexibility. A costbenefit may also be achieved, particularly if a component becomesdefective, since it is likely cheaper to replace or repair only one ofthe wavefront sensor 14 and the microscope 12, than to replace an entirepermanently integrated system.

The surgical device 10 may be used to improve and/or enhance a varietyof corrective procedures performed on the eye. In general, by providingthe ability to measure the refractive characteristics or other opticalproperties of a patient's eye while the patient remains lying in asurgical position, several of the limitations of existing systems may beovercome. Several examples of corrective eye procedures that may beenhanced by using the surgical device 10 are described below.

Cataract surgery generally involves replacing the natural lens of an eyeafter the natural lens has become unclear. Existing methods typicallyrequire measuring the physical dimensions of the eye with ultrasound,followed by calculating the refractive power of the artificial lens, orother replacement lens, to be inserted. Because the natural lens isunclear, these measurements are often difficult to make. Additionally,variations in the structures of the eye that cannot typically bemeasured using existing techniques may degrade the calculation.

The integrated surgical device 10 facilitates measurement of the eye'srefractive power before and/or immediately after the natural lens isremoved, without movement of the patient or the patient's eye, such thatthe true refractive power of the eye can be more accurately determined.For example, if it is determined that 42 diopters of power are neededfor a patient to see clearly at a predetermined distance, and after thenatural lens is removed the eye has only 22 diopters of power, then itcan easily and accurately be determined that 20 diopters of power mustbe introduced to the eye via the new lens being inserted.

With existing systems, once the lens is removed, and the doctor wishesto make a wavefront measurement, the patient typically has to be movedfrom the surgical table to a measurement device to make the refractivemeasurements. Because the patient is typically sedated, and there may bean incision in the patient's eye, and there are sterility requirementsto maintain, it is not practical to move the patient between surgicalsteps. By using the integrated surgical device 10, which is preferablysuspended above the patient's head, conversely, a surgeon may view thepatient's eye through the surgical microscope 12 while the wavefrontsensor 14 makes measurements of the eye with the natural lens removed.Accordingly, the patient, as well as the patient's eye, is able toremain motionless in the surgical position during the entire correctiveprocess.

A further challenge associated with cataract surgery is that once thereplacement lens is inserted into the eye, the replacement lens must bealigned to ensure that it is properly oriented and positioned. If, forexample, the replacement lens is not correctly centered, or is notperpendicular to the optical axis of the eye, or if the cylindricalportion (if astigmatic correction to the replacement lens is also beingperformed) is not oriented to the correct axis, refractive aberrationsmay be introduced, and the surgical outcome will therefore be degraded.The integrated surgical device 10 allows the surgeon to make refractivemeasurements of the eye, after the replacement lens has been inserted,which may be used to guide any required repositioning of the replacementlens.

Additionally, during cataract surgery, viscoelastic cushioning fluidsare typically injected into the eye to protect endothelium cells andother structures, and should be completely removed after the surgery iscompleted. The wavefront sensor 14 may be used to identify any remainingviscoelastic pockets (as wave distortions), and can therefore assist thesurgeon in removing all of the viscoelastic fluid.

By using the integrated surgical device 10, astigmatisms may also bereduced during the lens replacement procedure by means other than usinga replacement lens with a cylinder component. For example, the locationand size of any entry wound could be adjusted, the position of aparacentesis incision could be adjusted, as could any additionallamellar, radial, or arcuate cuts made, all while the surgeon receivesfeedback from the wavefront sensor 14 that may guide corrections madeduring the procedure.

Additionally, if a replacement lens is damaged during insertion, due tooverstress during gripping, nicks and cuts in the lens surface, ordamage to the centering haptics, wavefront measurements made after theinsertion can identify the damage. Accordingly, the replacement lens maybe replaced or repaired before the membrane that previously containedthe natural lens shrinks and tightens onto the replacement lens.

A process of introducing relaxing incisions into various locations ofthe eye, which causes the cornea to flatten out in predictabledirections, is often used to eliminate astigmatism of the cornea. Such aprocedure is often performed at the end of cataract surgery, forexample, to eliminate an astigmatism that was induced by the maincataract incision, or that had previously existed. The amount offlattening generally varies from patient to patient, however, and istherefore very difficult to precisely predict. By using the integratedsurgical device 10, the wavefront sensor 14 can make measurements duringthe surgical procedure to guide the position, depth, and length ofincisions made by the surgeon to achieve desired results.

Corneal transplant surgery, in which a small central portion, typically8 to 10 mm in diameter, of the cornea is cut from a donor's eye andgrafted into a correspondingly-sized hole cut into a recipient's cornea,may also be improved by using the integrated surgical device 10. Duringthe positioning and suturing of the donor's corneal tissue into therecipient's cornea, refractive errors are typically difficult tomeasure. Refractive errors may be introduced if, for example, thedonor's corneal tissue is not properly centered, rotated, or oriented inthe recipient's cornea, or if the sutures are too tight, too loose, ornot evenly tightened. If the recipient's eye is measured after thehealing process has completed, refractive errors are difficult, if notimpossible, to correct.

By using the integrated surgical device 10, a surgeon may measurerefractive changes in the eye while placing and suturing the donorgraft. Indeed, the recipient may remain lying on the surgical table, andthe surgeon may look directly into the visual axis of the recipient'seye, while the refractive measurements are being taken. Accordingly, therecipient does not need to be moved at any point during the transplantprocedure. Additionally, the donor cornea may be measured by thewavefront sensor to locate its optical axis to assist with bettercutting and/or placement of the cornea.

The integrated surgical device 10 may also be used to enhance LASIK(Laser-Assisted In Situ Keratomileusis) refractive surgery, or otherlaser-assisted surgical procedures. Several variations of laser visionsurgery require that a flap be cut from the surface of the cornea toexpose the stroma of the cornea to laser treatment. The laser reshapesthe stroma to a desired contour, after which the flap is replaced overthe reshaped stroma. If the flap is not precisely repositioned at itsoriginal location, if foreign matter is trapped inside the flap, if awrinkle is introduced during repositioning, and/or if a host of otherrepositioning errors occur, then the visual outcome of the procedurewill be degraded. The integrated surgical device 10 allows a surgeon tomeasure the refractive or optical properties of the eye while thesurgeon directly observes the eye, and while the flap is beingrepositioned, so that any positioning errors or other problems canquickly be corrected.

The integrated surgical device 10 may also be used during a ConductiveKeratoplasty (“CK”) procedure. CK is a refractive surgical procedure inwhich highly localized energy pulses, such as heat pulses or radiofrequency pulses, are applied to the collagen or stroma of the cornea toreshape the cornea to correct for refractive errors, particularlyhyperopia. Current methods typically require that the eye be measuredwith a conventional refractive device, which provides informationregarding how many energy pulses are required to reshape the cornea asdesired and identifies which regions of the cornea should receivepulses. The patient is then moved to a surgical location where theenergy pulses, typically 8 or more, are applied to the cornea, afterwhich the patient is moved back to the measurement device so that theeye may be re-measured.

The outcome of such a procedure is generally the result of a bestprediction, and the actual outcome is rarely exactly as desired due tovariability in the response of each individual cornea. If the cornea isunder-corrected, more pulses may be added later, but if the cornea isover-corrected, it is difficult, and sometimes impossible, to reversethe over-correction.

By using the integrated surgical device 10, the eye's refractivecondition may be measured after each pulse is applied (preferably aftera certain minimum number of pulses have been applied, for example, after6 pulses have been applied, since a complete correction will typicallynot occur until at least a certain minimum number of pulses have beenapplied), and the surgeon may therefore make guided corrections duringthe surgical procedure. The surgeon may, for example, alter theposition, size, quantity, and/or energy of the pulses applied ifmeasurements taken between successive pulses dictate that such stepsshould be taken. Additionally, the placement of the pulses is criticallyimportant, and the wavefront sensor may be used to help guide theplacement of each energy pulse.

A procedure for positioning an inlay in a cornea along the eye's visualaxis may also be aided by using the integrated surgical device 10. Insuch a procedure, after a flap is created over the cornea, either via aLASIK procedure or another procedure, an opaque disk or similarstructure with a small central aperture is placed in the cornea andtrapped inside the flap. The inserted disk creates the effect of asmaller aperture, resulting in the depth of view of the eye beingincreased. It is, however, extremely difficult to center the disk aboutthe eye's visual axis. By using the integrated surgical device 10, thewavefront sensor 14 can make measurements to determine the exactlocation of the eye's visual axis while the surgeon directly views theeye, which aids the surgeon in precisely positioning the disk in theproper central location.

In an alternative embodiment, the corneal inlay's central aperture maybe cut into the inlay by the laser after it has been placed in the eye.In such a case, the precise measurements of the wavefront sensor,coupled with the precise control of the laser placement, may result in amore accurate aperture position than if it were manually positioned.

The integrated surgical device 10 may also be used to control cornealdistortion during placement of inserts into the cornea. In the case ofmyopia, for example, the cornea is too steep and must be flattened. In atypical corrective procedure, slices are cut into the cornea, afterwhich tiny, curved strips are slid into the stroma of the cornea toexert a straightening force on the cornea that flattens the cornea. Byusing the integrated surgical device 10, the wavefront sensor 14 canmake measurements of the eye while the doctor directly views the eye,allowing the doctor to monitor the degree of flattening and to adjustthe process (e.g., to add more or different inserts) midstream.

The integrated surgical device 10 may further be used to measure andview the eye during a procedure for adjusting the tension of the ciliarymuscle and/or the ciliary process of the eye. In a typicalciliary-tensioning procedure, rings or other devices are inserted intothe sclera just beyond the limbus of the eye to exert a radiallyoutwardly pulling force on the ciliary muscle. The goal of thisprocedure is to expand the relaxed diameter of the ciliary muscle, whichin turn provides added tension in the ciliary muscle and removes some ofthe slack that has developed therein over the years. By using theintegrated surgical device 10, the wavefront sensor 14 can takemeasurements of the eye while the tensioning procedure is beingperformed under the surgical microscope 12, thus guiding the amount oftensioning required to achieve desired results.

Another corrective procedure involves removing tissue from the cornea,via mechanical slicing or another method, to modify the shape of thecornea. In one embodiment of mechanical tissue removal, an incision ismade in the side of the cornea to provide a split in the stroma of thecornea. A shallow spoon-shaped device is then guided into the split, anda blade is used to remove tissue below the spoon's edge plane, resultingin less corneal tissue thickness centrally than peripherally, and thus,corneal flattening (i.e., reduction in myopia). By using the integratedsurgical device 10, the wavefront sensor 14 can make measurements duringthe surgical procedure to guide the process and aid the surgeon indetermining how much tissue, at which locations, should be removed.

The natural lens of the eye may also be modified to correct refractivedefects in the natural lens. Some defects that may occur over timeinclude small opacities, protein buildup, and size increases in thelens. One method of modifying the natural lens involves removing tissuefrom the lens to correct vision loss associated with these and otherdefects. Even a small amount of material removal, however, can result ina large change in refraction. By using the integrated surgical device10, the wavefront sensor 14 can make measurements during the surgicalprocedure to guide the process and aid the surgeon in determining howmuch lens tissue, at which locations, should be removed.

Optical properties of the natural lens may also be modified byintroducing chemicals, or changing blood sugar levels, in a patient'ssystem. Using the integrated surgical device 10 during such a procedureallows a surgeon to measure the amount of change resulting from theintroduction of one or more chemicals, which can aid the surgeon inreaching a desired outcome.

The integrated surgical device 10 may also be used to aid in controllingor influencing the resulting shape of a lens that is injected into theeye as a liquid and that cures into a solid. Such a lens is commonlyreferred to as a “form in the bag” lens. Extreme precision is requiredto attain the desired resultant shape of the lens using such aprocedure. During the time period when the material changes from aliquid into a solid, the shape and index of refraction of the lens canbe manipulated. Using the integrated surgical device 10 allows a surgeonlooking through the microscope 12 to obtain wavefront data about thelens as it is being formed so that proper course corrections can be madeduring the curing process.

Advancements have been made in the ability to modify or tune thecharacteristics of an artificial lens after the lens has been insertedinto the eye and the eye has healed. By using the integrated surgicaldevice 10, a surgeon viewing the eye through the microscope 12 can makemodifications to the artificial lens while the wavefront sensor 14 makesmeasurements that can guide the procedure.

Several lenses are available that may be inserted into the eye, whilethe natural lens remains in place, to modify refractive characteristicsof the eye. The correct placement of such a lens is critical toachieving a desired outcome. The integrated surgical device 10 allows asurgeon to view the eye while making wavefront measurements, which aidsthe surgeon in selecting an appropriate lens and in positioning the lensin the correct central location along the visual axis of the eye.Additionally, the integrated surgical device 10 can verify the overallsuccess or failure of the procedure, which allows the surgeon to makeadjustments, while the patient remains on the surgical table, if theoutcome is not ideal. This not only improves efficiency, but also allowsre-accessing of an incision before it has healed, such that a newincision is not required to make corrections after a non-ideal outcome.

Another corrective procedure involves adding material into the cornea,measuring the resulting refractive condition of the eye, then removing aportion of the inserted material to achieve a desired result. Thewavefront sensor 14 of the integrated surgical device 10 may be used tomeasure the eye before the procedure to help determine a minimum amountof material to add, and may also be used to measure the eye after thematerial is inserted. The wavefront sensor 14 may then be used tomeasure the eye at various points of the procedure, which is performedunder the surgical microscope 12, to ensure that the correct amount ofmaterial is removed.

During many existing procedures, a patient's eye is measured with awavefront sensor at a first location, a treatment is calculated and/orplanned based on the measurements, and the patient is then moved to asecond location where the actual treatment is performed. Typically, theeye is measured while the patient is sitting upright, but the treatmentis performed while the patient is lying facing upward in a supineposition. When the patient moves from the upright position to the supineposition, the patient's eyes rotate, or “cyclotort.” To compensate forthis cyclotortion, dye marks are typically placed on the eye while thepatient is in the upright position so that the amount of cyclotortioncan be measured. By using the integrated surgical device 10, thewavefront measurements may be taken while the patient lies in the supineposition, with the cyclotortion present, and while the doctor is viewingthe eye. Accordingly, the intermediate step of marking the cornea andcompensating for the rotation is not required. The elimination of thisstep improves the efficiency of the process, and the precision of theorientation of the wavefront registration to the eye is enhanced.

While several corrective procedures have been described herein, it isunderstood that the integrated surgical device 10 may be used to enhanceany vision correction procedure by providing a surgeon the ability toview the eye simultaneously with making wavefront measurements of theeye. Thus, the surgeon may make wavefront measurements while the patientremains lying in the surgical position, and may course adjustments to aprocedure midstream without having to move the patient between surgicalsteps.

While several embodiments have been shown and described, various changesand substitutions may of course be made, without departing from thespirit and scope of the invention. The wavefront sensor 14, for example,could include a greater or lesser number of components arranged in anyconceivable configuration. The invention, therefore, should not belimited, except by the following claims and their equivalents.

What is claimed:
 1. A surgical device for measuring properties of aneye, comprising: a surgical microscope providing a stereoscopic firstfield of view, the surgical microscope comprising a first housing and anobjective lens; and a wavefront sensor for performing refractivemeasurements of the eye, the wavefront sensor providing a second fieldof view and comprising a different second housing the second housingcomprising an optical passageway therethrough, and a combining opticalelement located in the second housing along the optical passageway,wherein the combining optical element is positioned to receive lightthat reflects from the eye and to send a first portion of the lightreflected from the eye outside the second housing to the surgicalmicroscope via the optical passageway through the second housing, and tosend a second portion of the light reflected from the eye to one or moreoptical components within the second housing, wherein the second fieldof view of the wavefront sensor is optically aligned with the firstfield of view of the surgical microscope, wherein the wavefront sensordoes not compromise the focal length of the surgical microscope, andwherein the wavefront sensor and the surgical microscope are notintegrated with a laser for performing refractive correction on the eye.2. The surgical device of claim 1 wherein the footprint of the wavefrontmeasuring device is less than 9 inches long and less than 5 inches wide.3. The surgical device of claim 1 wherein the device is configured topermit the eye to be simultaneously viewed via the surgical microscopeand measured via the wavefront sensor.
 4. The surgical device of claim 1wherein the wavefront sensor includes one or more diffractive opticalcomponents for producing a measurable image of a wavefront reflectedfrom the eye.
 5. The surgical device of claim 4, wherein the one or morediffractive optical components comprise a first grating and a secondgrating separated by an integer multiple of a Talbot distance, the firstand second gratings being rotated with respect to one another.
 6. Thesurgical device of claim 1, wherein the combining optical elementcomprises a combiner mirror or a beam splitter.
 7. The surgical deviceof claim 1, wherein the combining optical element is configured to sendlight in the visible spectrum to the surgical microscope and to sendlight in the infrared spectrum to the one or more optical componentswithin the second housing.
 8. The surgical device of claim 1, whereinthe housing of the wavefront sensor is adapted to attach to the housingof the surgical microscope.
 9. The surgical device of claim 8, whereinthe housing of the wavefront sensor comprises a fastener for removablyattaching to the housing of the surgical microscope.
 10. The surgicaldevice of claim 1, wherein the surgical microscope comprises binocularoptics.